JPS5814609A - Amplifier - Google Patents

Abstract

PURPOSE:To reduce the size of an amplifier, by attenuating the input signal applied to an input terminal by an attenuator to then amplify the attenuated input signal by the 4th amplifier and then adding the output of the 4th amplifier to the input signal of the 3rd amplifier. CONSTITUTION:The 1st amplifier 2 amplifies an input signal e1; the 2nd amplifier 4 amplifies the difference signal between the output signals of the amplifier 2 and the signal e1; and the 3rd amplifier 5 amplifies the sum signal of the output signal of the amplifier 4 and the signal e11. The output signals of the amplifiers 1 and 5 are supplied to a load via the 1st and 2nd impedances 6 and 7 respectively. In this case, an attenuator 10 and the 4th amplifier 11 are provided to secure the virtual coincidence between the phase of an output signal e5' of the 3rd amplifier 5 and the output signal of a load terminal 8. As a result, the output power of the amplifier 2 is supplied to a load resistance 9 with high efficiency with no loss caused at the amplifier 5. Thus the amplifiers 2 and 5 can be miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the efficiency of feedforward amplifiers.Recently, tweed amplifiers have been considered. In the figure, the input terminal of the first amplifier 20 is input terminal 1! 1! At the same time as the second amplifier 111440 non-inverting input terminal! It is connected to the output terminal 8 via the impedance 6 of the output terminal aJI11 and to the inverting input terminal of the second amplifier 1140 via the attenuator 3. The input terminal of the third amplifier 5 is connected to the output terminal of the second amplifier 4 and to the output terminal 8 via a second impedance 7 in the form of an output terminal. The output terminal 8 is grounded via a load resistor 9. In the above configuration, the distortion generated due to the characteristics of the first amplifier 2 having a nonlinear amplification degree is extracted by the second amplifier 4, amplified by the amplifier 5 at tIX3, It operates so that the distortion components are combined in opposite phase and canceled by the impedance 7, and a distorted 4h output signal is obtained at the output terminal 8.

However, in the above, the third amplifier 5 is the first amplifier 2.
Since we are dealing with distortion components generated in the third amplifier 5, the output terminal of the third amplifier 5 does not contain any signal components. That is,
The input signal applied to the input terminal 1 is el, the amplification degree of the first amplifier 2 is divided into an axillary component and a nonlinear component, the undistorted component is A1, the distortion component is D, and the attenuation ratio of the attenuator 30 is 1
/X, the amplification degree of J2 is Mu2. The amplification degree of the third amplification IIs is 3. If the impedance values of the 1st and 20th impedance numbers and 7 are zl and z2, respectively, *
The output level of the output terminal of the SO amplifier 6 is as follows: If we assume that MU1 = MU = S - → MU 3 1 ・−−−−−−−−−−−−−
----------(2) And increase of jll @@20 Output level of output terminal es line el=Mu1 sB + D @1 ----------
−−−−−−−−−−− (3) Therefore, by holding, the tenth amplification I! The distorted fist power (D・1) generated from 2 is removed, and output No. 1 without distorted fist is obtained at the output terminal 8. The impedance of the construction is 6 and the load resistance is 9! A portion of the output signal of the tenth amplifier flows into the output terminal of the *SO amplifier 50 according to the ratio of the impedance value of the load resistance and the impedance value of the impedance of 1g2. However, the amplifier 5 of 11g3 generates a large amount of heat, and due to this loss of output power, the output power of the 10th amplifier 20 cannot be efficiently supplied to the load resistor 9, and both the Ml and gso amplifiers %0
However, it is also extremely uneconomical.

The ninth way to reduce such power loss is to make the impedance value of the second impedance 7 a sufficiently large value compared to the impedance value of the load resistor 9. As shown in the figure, it is necessary to increase the output amplitude of the 30th amplifier 41i (increase the amplifier 3) in order to cancel the distortion, and if the power supply voltage of the #E30 amplifier 5 has to be increased to a very high voltage. It causes disadvantages that should not be avoided.

The present invention provides an efficient tweed forward amplifier that improves the above-mentioned drawbacks.

FIG. 2 shows an example of the present invention. In FIG. 0, there is a dot shape different from that in FIG. Since the output is added to the input signal of the 30th multiplier 50 by the adder 12 in only 9 steps, the same reference numerals are given to the parts having the same functions as in FIG. Although omitted, the attenuation ratio of the attenuator 1410 is IA, and the amplifier 1 of s4
If the amplification degree of 1 is 4, then the output terminal O level of the fourth amplifier 11 is 1! #i・u ”-”mu4・! Accordingly, the level e51 of the output terminal of the 30th multiplier 5 is expressed by the above equation! If the attenuator 10 and M4K) are set so that the level of the signal component of 5) becomes the output 111 level e8 of the output terminal 8, the output terminal 1 and the 30th amplifier Since the level of the output terminal 5 is driven at the same level by the signal part, the large output signal line of the first amplifier 2 does not flow into the third amplifier 5, and the second impedance 7 The current value 17 flowing through is a small current value corresponding to the distortion component of . Therefore, the output power of the first amplifier 4112 is efficiently supplied to the load resistor 9 without loss in the amplifier 5 of the first amplifier 4112. Thus, according to the present invention, the output power is efficiently supplied to the load resistor 9. Since the first amplifier 2% output power is supplied to
It may be a small amplifier of H&S or a small size, or it may be a simple amplifier like the third amplifier 54. Of course, if the signal level can be set to be equal to the signal level of , the attenuator 10 can be omitted.

[Brief explanation of the drawing]

FIG. M1 is a circuit diagram showing an example of an increase @ penalty to which the present invention can be applied, and FIG. 2 is a circuit diagram showing an embodiment of the present invention. 2.4 and 5 in the figure are the 1st, 2nd and 30th increase @
6 and 7 are impedances of the first and J2, and 9 is a load resistance. Patent applicant Nippon Columbia Co., Ltd.37

Claims (1)

[Claims] a first amplifier that amplifies the human power signal; a second amplifier that amplifies the output signal of the first amplifier; a second amplifier that amplifies the zero difference signal from the human power signal; and the output ID of the second amplifier and the input a third amplifier for amplifying the output signals of the first and third amplifiers, respectively.
The amplifier is characterized in that the output signal of the third amplifier is supplied to the load via an impedance of 0, and the phase of the output signal of the third amplifier is offset from the output signal of the load terminal.